Devices and Methods for Reducing Mitral Valve Regurgitation

ABSTRACT

A mitral valve annulus reshaping device includes at least a portion that is formed of a biocompatible shape memory alloy SMA having a characteristic temperature, A f , that is preferably below body temperature. The device is constrained in an unstable martensite (UM) state while being introduced through a catheter that passes through the venous system and into the coronary sinus of the heart. The reshaping device is deployed adjacent to the mitral valve annulus of the heart as it is forced from the catheter. When released from the constraint of the catheter, the SMA of the device at least partially converts from the UM state to an austenitic state and attempts to change to a programmed shape that exerts a force on the adjacent tissue and modifies the shape of the annulus. The strain of the SMA can be varied when the device is within the coronary sinus.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.12/838,189, filed Jul. 16, 2010; which is a continuation of U.S.application Ser. No. 11/655,710, filed Jan. 18, 2007, now U.S. Pat. No.7,758,639; which is a continuation of U.S. application Ser. No.10/359,016, filed Feb. 3, 2003, now U.S. Pat. No. 7,314,485; all ofwhich are incorporated by reference as if fully set forth herein.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention generally pertains apparatus and a method fortreating mitral insufficiency and, more specifically, for treatingdilation of the mitral valve annulus of the human heart and concomitantblood leakage, by using force applied with a device formed at least inpart of a shape memory alloy that is conditioned to a martensite statebefore being inserted into a venous system of a patient and advancedinto the patient's coronary sinus.

BACKGROUND OF THE INVENTION

Mitral insufficiency is the inability of the mitral valve to closecompletely and can occur for several reasons, such as ischemic disease,degenerative disease of the mitral apparatus, rheumatic fever,endocarditis, congenital heart disease, and cardiomyopathy. Because themitral valve does not close completely, “mitral regurgitation” occurs.Blood thus leaks back through the mitral valve, and the heart becomesless efficient. Over time, the reduced pumping efficiency can cause theheart to become enlarged.

The four major structural components of the mitral valve are theannulus, the two leaflets, the chorda, and the papillary muscles. Anyone or all of these components, in different combinations, may beinjured or suffer from a congenital defect and cause the insufficiency.Annular dilatation is a major component in the pathology of mitralinsufficiency, regardless of its cause. Moreover, many patientsexperience mitral insufficiency primarily, or only, due to posteriorannular dilatation. Annular dilation can occur when the annulus of theanterior leaflet does not dilate because it is anchored to the fibrousskeleton of the base of the heart.

Studies of the natural history of mitral insufficiency have determinedthat totally asymptomatic patients with severe mitral insufficiencyusually progress to severe disability within five years. At present, thepreferred treatment for this condition consists of either mitral valvereplacement or repair; however, both types of treatment require openheart surgery. Replacement can be performed using either mechanical orbiological valves.

Replacement of a mitral valve with a mechanical valve carries the riskof thromboembolism (due to formation of a clot) and requires that ananticoagulant be administered to the patient, with all its potentialhazards, whereas a biological prostheses replacement may suffer fromlimited durability. Another hazard with replacement is the risk ofendocarditis (inflammation of the endocardium). These risks and otherrelated complications of valve replacement are greatly diminished ifvalve repair is carried out, rather than valve replacement.

Mitral valve repair is theoretically possible if a substantially normalanterior leaflet is present. The four basic techniques for repairinclude: (a) the use of an annuloplasty ring; (b) quadrangular segmentalresection of a diseased posterior leaflet; (c) shortening of elongatedchorda; and (d) transposition of posterior leaflet chorda to theanterior leaflet.

Annuloplasty rings are employed to achieve a durable reduction of theannular dilatation. Typically, annuloplasty rings are sutured along theposterior mitral leaflet adjacent to the mitral annulus in the leftatrium. The installation procedure employed depends upon the specificannuloplasty ring being installed. For example, a Duran ring encirclesthe valve completely, whereas others types of rings are open towards theanterior leaflet. The ring can either be rigid, as in a Carpentier ring,or flexible, but non-elastic, like the Duran ring or a Cosgrove-Edwardsring.

Effective treatment of mitral insufficiency currently requiresopen-heart surgery, involving a total cardiopulmonary by-pass, aorticcross-clamping, and temporary cardiac arrest. For certain groups ofpatients, open-heart surgery and the associated procedures that must beperformed are particularly hazardous. It is likely that elderly patientsand patients with a poor left ventricular function, renal disease,severe calcification of the aorta, previous cardiac surgery, or othercardiovascular diseases, would particularly benefit from a less invasiveapproach, even if repair of the mitral valve is incomplete. The currenttrend towards less invasive coronary artery surgery, withoutcardiopulmonary by-pass, as well as percutaneous transluminal coronaryangioplasty (PTCA) will also call for the development of a less invasivemethod for repair of the mitral insufficiency that is often associatedwith PTCA.

To perform typical open surgical procedures in ways that are lessinvasive will likely require use of technology for storing ortransmitting energy so that apparatus for implementing the treatment canbe delivered within a limited space, and positioned and released inremote locations in the body. Hydraulic conduits such as those used toinflate balloon catheters, and an electrical current have been employedto actuate devices remotely in the human body. However, one of the mostreliable and effective remote actuation methods utilizes self actuatingcomponents formed of a shape memory alloy (SMA) that releases storedstrain energy at a desired location within the body of a patient.

Materials capable of shape memory are well known. A structural elementmade of such materials can be deformed from an original, heat-stableconfiguration to a second, heat-unstable configuration. In theheat-unstable configuration, the element is said to have shape memorybecause, upon the application of heat alone, the element can be causedto revert, or to attempt to revert, from its deformed configuration toits original, heat-stable configuration. The metal element “remembers”its programmed shape. Programming is accomplished by thermally ormechanically stressing the element, while bending it into a desiredshape.

Among certain metallic alloys, the shape memory capability occurs whenthe alloys undergo a reversible transformation from an austenitic stateto a martensite state, with a change in temperature. This transformationis sometimes referred to as a thermo-elastic martensite transformation.An element made from such alloys, for example a hollow sleeve, is easilyloaded and deformed from its original configuration to a newconfiguration if it has been cooled below the temperature at which thealloy is transformed from the austenitic state to the martensite state.The temperature at which this transformation from austenite tomartensite begins is usually referred to as M_(s) (martensite start),and the temperature at which the transformation is complete is M_(f)(martensite final). When an element that has been thus deformed iswarmed to the temperature at which the alloy starts to recover back toan austenite phase, referred to as A_(s), the deformed object will beginto recover to its programmed shape. Assuming that the element isunconstrained, it will assume its programmed shape when it has beenfully transformed to an austenitic state (where A_(f) is the temperatureat which the recovery is complete).

Many shape memory alloys (SMAs) are known to display stress-inducedmartensite (SIM) characteristics. When an SMA element exhibiting SIM isstressed at a temperature above M_(s) (so that the austenitic state isinitially stable), but below M_(d) (the maximum temperature at whichmartensite formation can occur even under stress), it first deformselastically and then, at a critical stress, begins to transform to amartensite state.

Depending on whether the temperature is above or below A_(s), thebehavior of an SMA when the deforming stress is released differs. If thetemperature is below A_(s), the thermally induced martensite is stable;but if the temperature is above A_(s), the martensite is unstable, sothat the SMA transforms back to austenite and returns (or attempts toreturn) to its original shape. As used herein, the term “unstablemartensite” or (UM) describes a martensite state of an SMA alloy that isat or above the alloy's A_(s) temperature. Under certain circumstances,this effect is actually seen in almost all alloys that exhibit athermo-elastic martensitic transformation, along with the shape memoryeffect. However, the extent of the temperature range over which UM isobserved and the stress and strain ranges for the effect vary greatlywith the alloy.

Various proposals have been made to employ shape memory alloys in themedical field. For example, U.S. Pat. No. 3,620,212 to Fannon et al.teaches the use of an SMA intrauterine contraceptive device; U.S. Pat.No. 3,786,806 to Johnson et al. teaches the use of an SMA bone plate;and U.S. Pat. No. 3,890,977 to Wilson teaches the use of an SMA elementto bend a catheter or cannula.

These prior art medical SMA devices rely on the property of shape memoryto achieve their desired effects, i.e., they rely on the fact that whenan SMA element is cooled to its martensitic phase and is subsequentlydeformed, it will retain its new shape. But when the deformed SMA iswarmed to its austenitic phase, the original shape will be recovered.Heating a medical SMA device to activate a recovery to a programmedshape within a patient's body is quite complicated and is generally notpractical, because complex and sometimes unreliable heat energy sourcesare needed to cause the change in state of the metal. In many SMAs,there is a relatively large hysteresis as the alloy is transformedbetween its austenitic and martensitic states, so that thermal reversingof the state of an SMA element may require a temperature excursion ofseveral tens of degrees Celsius. The use that can be made of SMA medicaldevices in the body of a human patient is limited because of thesefactors and because: (a) it is inconvenient to engage in any temperaturemanipulation of a device in-vivo; and, (b) human tissue cannot be heatedor cooled beyond certain relatively narrow limits (approximately 0-60degrees C. for short periods) without suffering temporary or permanentdamage.

It would therefore be desirable to use the advantageous property ofshape memory alloys, i.e., their ability to return to a programmed shapeafter experiencing a relatively substantial deformation, in mitral valvetherapy, without requiring the delicacy of alloying control and/or thetemperature control of placement or removal needed by thermallyactivated SMA devices.

Nickel titanium SMA compositions can be tuned with appropriate heattreatments to adjust the A_(f) temperature of the material. Compositionscomprising nickel, in about 50 to 60% Ni atomic percent (hereinafterreferred to as at. %), using Ti for the remainder of the composition,can have characteristic A_(f) temperatures ranging from 0-100° C. Byheat-treating these alloys at or near approximately 500° C., it ispossible to precipitate nickel in or out of the Ni—Ti matrix so as toadjust the A_(f) to a specific and desired temperature.

The A_(f) temperature of a SMA can be readily determined. By deforming acooled SMA sample (comprising stable thermally induced martensite at atemperature well below its A_(f)) from its programmed shape and thenincreasing its temperature, a distinct temperature can be identified atwhich the sample has recovered-fully to its programmed shape. It is atthis A_(f) temperature that the entire sample has transformed back to anaustenite state. The A_(f) temperature of local regions of a componentcan be adjusted individually and determined in a similar manner, also.

By adjusting the SMA's characteristic A_(f) below body temperature, thealloy will exhibit super-elastic or pseudo-elastic properties at bodytemperature, allowing it to experience as much as 8% strain and stillfully recover. In this application, the SMA is initially austenitic and,under no load, it is not strained. Upon loading the device, the straindeveloped in the SMA causes it to undergo a phase transformation to UM.Upon unloading, the SMA that is UM will recover to its programmed shapeand revert back to an austenitic phase. During loading and unloading,SMA alloys are internally stressed and deliver resistance forces ofdifferent magnitudes at the same strain state. The loading curvedescribes loading (stress) versus strain required to deform an elementfrom its programmed shape while the unloading curve is descriptive ofthe load (stress) versus strain curve exhibited while the element isrecovering to its programmed shape after being loaded, and thusrecovering to a zero strain state. The unloading curve can be much lowerin magnitude than the loading curve. This bimodal (BM) elastic effect(i.e., the hysteresis between the two curves) can only be accomplishedat a constant temperature if the material is conditioned to a state ofUM (along the loading curve).

A device made from an SMA alloy can be manipulated from one performancelevel to another simply by varying the load applied to the device,thereby changing its level of stored strain energy. The bimodal (BM)effect between the curves enables a medical device to be assisted, usingforce, to a different equilibrium condition as the device bears on softtissue. A medical device made from this family of SMAs can be deployedfrom a delivery system (allowing it to partially recover towards aprogrammed shape along its unloading curve) to achieve a balanced, lowforce condition in a patient's body. Using hydraulic, pneumatic,electrical, heat energy, or mechanical force, the device can be assistedto further displace tissue, by adjusting the load along the unloadingcurve, to approach a zero strain state. As the assisting force isremoved, an elastic recoil of the tissue will displace the device in areverse direction, towards a slightly more deformed shape, thus causingthe alloy to resist bending more effectively by forcing it to theloading curve (i.e., to a stiffer condition). This bimodal (BM) effectacts as a one-way ratchet with minimal moving parts and thus enableseffective and reliable adjustment of load bearing elements in the humanbody to achieve a desired effect on adjacent tissue.

UM can be stress induced in SMAs by imparting sufficient stress totransform an SMA element from an austenite to a UM state. This type ofUM is referred to as strain induced. Also, SMA elements can be cooled toform stable, thermally induced martensite. The SMA element can then beeasily deformed to a new shape, constrained in the new shape, and thenwarmed to a temperature above the A_(f) temperature of the SMA to createa UM state. There are also combinations of these conditioning techniquesthat will accomplish the same UM condition. These conditioning methodsinevitably create a condition of stored strain energy sufficient toenable self-actuation and adjustment of medical devices remotely placedin a patient's body.

An SMA element with an A_(f) temperature adjusted above body temperaturewill remain in a state of stable martensite in the human body ifunconstrained. At body temperature, an SMA element in this conditionwill not recover to an original programmed shape upon loading andunload. If sufficiently loaded, its shape will be altered and it willremain in the new shape. In this bending process, SMA comprisingprimarily nickel and titanium, as described above, work hardens at ahigh rate, which increases the alloy's effective stiffness and strength.A device that is self-actuating must avoid these problems if it is to bepractical for use in modifying the annulus of a mitral valve to correctmitral valve leakage. Accordingly, such a device should be formed usingan SMA that is super-elastic at body temperatures, so that whenunloaded, the device will recover to its programmed shape when unloadedwithin the body of a patient.

SUMMARY OF THE INVENTION

The present invention takes advantage of the coronary sinus beingadjacent to the mitral annulus, and the properties of SMAs that areconditioned to a state of UM. Using the present invention, mitral valverepair can be carried out using catheter-guided techniques to deploy adevice within the coronary sinus, so that the device self actuates whenreleased from a constraint.

According to the present invention, a device for treatment of mitralinsufficiency is sized so as to be capable of insertion into thecoronary sinus and is formed at least in part of an SMA having twostates. In a first state, the device has a shape adaptable to fit theshape of the coronary sinus, but when allowed to transform to the secondstate, the device assumes a second shape that enables a force to beapplied to modify the mitral valve annulus in a way that reduces mitralvalve regurgitation. The transformation from the first shape to thesecond shape is facilitated at least partially by utilizing the releaseof strain energy as the device or a portion thereof is unconstrained andallowed to change from a state of UM to a lower strain condition. Thus,the device may change to an austenite state upon being unloaded. UM isgenerally induced at strain levels above about 1.0%, and more typically,at strain levels above about 1.5%.

As used herein, the term “coronary sinus” is meant to refer to not onlythe coronary sinus itself, but in addition, to encompass the venoussystem associated with the coronary sinus, including the great cardiacvein, the coronary sinus, the junction between the cardiac vein and thecoronary sinus, and the right atrium of the human heart. The presentinvention is intended to be delivered into the coronary sinus, becausethe coronary sinus is advantageously located adjacent to the mitralvalve of the human heart and in a location to which the device can bemaneuvered through peripheral vasculature, using common or customcatheter-based instruments, without the need for an open chestoperation.

According to another aspect of the present invention, a method ofaltering the shape of the mitral valve annulus includes the steps ofinserting a device at least partially comprising an SMA constrained in astate of UM, into the coronary sinus, and releasing the constraint toallow the device to recover towards a previously programmed shape andlower strain state. In yet another aspect of the invention, a force isapplied to the device while it is positioned in the coronary sinus so asto adjust the intrinsic stiffness and shape of the device and therebyalter the shape of the coronary sinus to modify the shape of the mitralvalve annulus.

Preferably, the device is formed from an SMA that has been treated sothat it is super-elastic within the body of a patient. The super-elasticproperties are employed by the device in its change of configurationbetween constrained and relaxed states. An appropriate treatment caninvolve a combination of cold working (for example by swaging, drawingor, in particular, by mandrel expansion) and heat treatment at atemperature that is less than the recrystallization temperature of thealloy while the device is constrained in the configuration resultingfrom the cold work. A plurality of the cold work and heat treatmentsteps can be used. The device can then be deformed towards theconfiguration of its first shape in its constrained first state, thedeformation being recoverable and substantially elastic. In this way,deformations of up to 8% strain can be imparted and recoveredsubstantially elastically.

Alloys from which the device can be made include Ni—Ti based alloys,especially Ni—Ti binary alloys, such as those in which the nickelcontent is at least about 50% at. %, and preferably, at least about 50.5at. %. The nickel content will usefully be less than about 54 at. %, andpreferably, less than about 52 at. %. The device may be produced fromother Ni—Ti based alloys, including alloys with ternary and quaternaryadditions. Examples of other elements that can be incorporated asadditions to the alloy include Fe, Co, Cr, Al, Cu, and V. Other elementscan be present in amounts up to about 10 at. %, and preferably, up toabout 5 at. %.

In still another aspect of the present invention, a device is definedfor treatment of mitral insufficiency. The device has an elongate bodywith dimensions selected so that the device can readily be inserted intothe coronary sinus and at least in part is formed of a material havingtwo states, including a first state in which the device has a shape thatis adaptable to fit the shape of the coronary sinus, and a second statein which the device is transformed from the said first state to assume ashape having either a reduced radius of curvature or an increased radiusof curvature. The radius of curvature of the coronary sinus is thusmodified by the device, as well as the radius of the circumference ofthe mitral valve annulus, when the elongate body is positioned in orthrough the coronary sinus. The distal and proximal ends of the device,and points in between, apply localized forces on the mitral annulus atone or more discrete locations.

The transformation from the first to the second state is facilitatedthrough the use of SMA constrained in a UM state, utilizing the releaseof strain energy as the device or portion thereof is unconstrained andallowed to transform from UM to a lower strain condition (and in atleast one embodiment, to transform to stable austenite) upon unloading.The constraining element can be a typical catheter, e.g., of the typecommonly used to deliver devices such as arterial stents.

An optimal method to use the above-described device includes deployingthe device and then assisting it into a more optimal shape using adrawstring (tether) or other element, to vary the length of the devicealong one side and thereby cause a curvature enhancement of the device.This mechanical assistance will alter the stiffness and enhanceperformance of the device by utilizing the BM effect of UM, as describedabove.

In another embodiment, the device includes one or more stents that areformed of SMA alloy having UM properties for self-deployment andadjustment. In this embodiment, the device may further include wiresand/or spring elements for shortening the distance between the stentsections using UM properties. The stent sections may be actuated byforce provided by balloon devices or they may be self-actuated by thetransformation from UM, as described above. Stent radial stiffness andwire tension performance is adjustable using mechanical or balloondevices to enable a new stiffness condition using the BM effect of UM.The devices could optionally include dedicated anchor structures thatapply a low expansive force against the wall of the coronary sinus.

In one preferred embodiment, the present invention is directed to anassembly that includes a tubular delivery device in which the mitralannulus shaping device is disposed and constrained, prior to insertioninto a patient's body through a catheter. The constraint imparts astrain in excess of 1.5% on a region of the mitral valve annulusreshaping device so that it is UM at normal body temperature.

Still another aspect of the present invention is directed to aconstruction in which a mitral annulus shaping device can be constrainedin a strained configuration for delivery into the coronary sinus withina hollow member, such as a catheter. A suitable catheter might beformed, for example, from a polymeric material that constrains themitral annulus shaping device while disposed in the catheter, and whichfacilitates discharge of the mitral valve annulus reshaping device fromthe catheter.

The mitral valve annulus reshaping device can be discharged from thedelivery device either by advancing the mitral annulus shaping deviceforward with respect to the delivery device, or by withdrawing thedelivery device from the site at which the mitral annulus shaping deviceis being deployed.

The configuration of the delivery device is selected so that it canproperly contain the mitral valve annulus reshaping device and withstandthe elastic forces exerted by the device prior to discharge from thedelivery device. Preferably, the delivery device has a minimum wallthickness necessary to satisfy these criteria. A constraint providedaccording to the present invention has the advantage of beingthin-walled and flexible in bending, while also having sufficient radialstiffness to be able to withstand the forces exerted by the mitralannulus shaping device as it attempts to recover, even when these forcesare applied over a long period of time, at temperatures above bodytemperature.

Preferably, the mitral valve annulus reshaping assembly includes meansfor facilitating release of the mitral valve annulus reshaping devicefrom within the delivery device. For example, one of the contactingsurfaces of the shaping device and the delivery device can be coatedwith a material that reduces friction effects between those surfaces.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 illustrates the stress-strain behavior of an alloy, whichexhibits stress versus strain behavior due to induced martensite whenthe A_(f) temperature is at or above the temperature of a human body;

FIG. 2 illustrates the stress-strain behavior of an alloy, whichexhibits constant stress versus strain behavior due to inducedmartensite when the A_(f) temperature is below body temperature;

FIG. 3 illustrates the stress-strain behavior of an SMA, wherein theA_(f) temperature of the material is below body temperature, and whereinthe SMA has been transformed to a state of martensite for insertion intoa delivery system, constrained as UM while delivered, then partiallyrelaxed to a lower strain state in the coronary sinus, assisted with anexternal force to a further relaxed lower strain state, and made stifferdue to modulation of the SMA bias stiffness as the material is loadedwith force from tissue recoil, upon removal of the external assistingforce;

FIG. 4 is a superior view of a human heart with the atria removed toexpose a plurality of valves and show the relationship between themitral valve and the coronary sinus;

FIG. 5 is a pre-curved inner dilator and a straight guide catheter foruse in introducing a mitral valve annulus reshaping device into thecoronary sinus;

FIG. 6 is a delivery assembly for a mitral valve reshaping deviceconstrained in a delivery cartridge adapted to couple to the catheter ofFIG. 5, to enable the reshaping device to be advanced with an includedpusher into and through the catheter to a delivery site in a humancoronary sinus;

FIG. 7 shows the human heart of FIG. 4, with a mitral valve annulusreshaping device constrained within a catheter used to introduce thedevice into the coronary sinus;

FIG. 8 shows the human heart of FIG. 4, with a mitral valve annulusreshaping device that has been deployed outside the constraint of thecatheter and allowed to transform to a second state in the humancoronary sinus, so that the device now has a reduced radius ofcurvature, producing a force that acts on the annulus of the mitralvalve to modify its shape;

FIG. 9 shows the human heart of FIG. 4 and the mitral valve annulusreshaping device of FIG. 8, after tissue rebound has increased thestrain in the SMA of the device so that it has an increased radius ofcurvature;

FIG. 10 shows the human heart of FIG. 4 and a side elevation view of anassembly including a pusher, a mitral valve annulus reshaping device,and a tether for modifying the radius of curvature of the device andvarying the strain in the device;

FIG. 11 is an enlarged side elevational view of the mitral valve annulusreshaping device and tether line shown in FIG. 10;

FIG. 12 shows the human heart of FIG. 4, with a mitral valve annulusreshaping device that has been allowed to transform to a second state,in the human coronary sinus, where the second state increases the radiusof curvature of the mitral valve annulus;

FIG. 13 shows a mitral valve annulus reshaping device comprisingdedicated anchor elements that are self-actuated from a state ofunstable martensite to a second state with an SMA spring connector andbias stiffness adjusting tether in a human coronary sinus;

FIG. 14 is the mitral valve annulus reshaping device of FIG. 13, whereinthe SMA spring connector has been adjusted to increase the springelement stiffness and thus straighten the coronary sinus to reshape themitral valve annulus;

FIG. 15 illustrates the coronary sinus and mitral valve and shows amitral valve annulus reshaping device comprising stent elements that areself-deploying from a state of unstable martensite to a second statewith an SMA spring connector and bias stiffness adjusting tether in ahuman coronary sinus;

FIG. 16 is a schematic illustration showing a programmed shape ofanother mitral valve annulus reshaping device having a wire or archedleaf spring with a radius of curvature, R;

FIG. 17 is a schematic diagram illustrating the mitral valve annulusreshaping device of FIG. 16 disposed within the coronary sinus andpartially straightened to have a larger radius of curvature, R′; and

FIG. 18 is a schematic diagram illustrating the mitral valve annulusreshaping device of FIGS. 16 and 17, after the device has been tunedwith a tether to have provide a different force against the mitral valveand to have an even larger radius of curvature, R″.

DETAILED DESCRIPTION OF THE INVENTION

To understand the present invention, it is necessary to understandaustenite to martensite transformations that occur in a SMA andunderstand how SMA can be used advantageously in the coronary sinus formodifying the mitral valve annulus. After discussing these concepts, thedisclosure will turn to specific devices, methods and assemblies of thepresent invention.

FIGS. 1-3 illustrate stress-strain curves for martensite-austeniticconversion of an SMA. In these Figures, the SMA is warmed to human bodytemperature (herein considered to be about 37° C.), which is betweenM_(s) and M_(d) for the SMA, so that the SMA is initially austenitic.The following discussion assumes that M_(s) is equal to M_(f), and thatA_(s) is equal to A_(f). FIG. 1 shows the case when the A_(s)temperature is adjusted higher than 37° C., so that any martensiteformed by an applied stress is stable; while FIGS. 2 and 3 show caseswhere the A_(f) temperature is adjusted below 37° C., so that austenite,at zero stress, is the only stable state, and any martensite that isformed, is unstable.

In FIG. 1, when a stress is applied to the SMA, it deforms elasticallyalong line OA. At a critical applied stress, σ_(M), the austenitic SMAbegins to transform to martensite. This transformation takes place atessentially constant stress until the alloy becomes fully martensitic atpoint B. From that point on, as further stress is applied, themartensite yields first elastically and then plastically (only elasticdeformation is shown along path BC). When the stress is released, themartensite recovers elastically to point D, at which there is zeroresidual stress, but a non-zero residual strain. This behavior wouldnormally describe classic plastic deformation, except in this case, thedeformation is not plastic, because the SMA can recover with theapplication of heat energy. Because the temperature is below this SMA'sA_(s) temperature, the deformation is not recoverable until the SMA isheated above A_(s), resulting in a reversion of the SMA to austenite. Atthat point, if the sample is unrestrained, the original (programmed)shape will be essentially completely recovered; but if constrained, theSMA will recover only to the extent permitted by the constraint.However, if the material is then allowed to re-cool to the originaltemperature at which it was deformed, the stress produced in the samplewill be constant, regardless of the strain, provided that the strainlies within the “plateau” region of the stress-strain curve, i.e., alongline AB. Thus, for a strain between ε_(B) and ε_(A), the stress will beσ_(M), and a known, constant force (calculable from σ_(M)) can beapplied over a relatively wide strain range.

In FIG. 2, when a stress is applied to the SMA, it deforms elasticallyalong line OA, then along line AB, while transforming from austenite toa martensite state. By straining the alloy further, the martensite canbe deformed to point C, just as in FIG. 1. However, the stress-strainbehavior upon unloading is significantly different, since the human bodytemperature is above the A_(s) temperature of this alloy and the stablephase is therefore austenite. The martensite at point C is thus UM. Asthe stress is removed, the alloy recovers elastically from C to D and,at a critical stress, σ_(A), the SMA reverts to austenite withoutrequiring a change in temperature. Thus, reversion occurs at essentiallyconstant stress. Finally if the stress is removed from the revertedaustenite, it recovers elastically along line EO. The recoverabledeformation associated with the formation and reversion of UM has beenreferred to as pseudoelasticity. While σ_(M) may be comparatively high,e.g., more than 50 ksi, σ_(A) is usually substantially lower, e.g., lessthan 10 ksi, thereby creating a constant-force spring with an effectiveworking strain range of about 5% (ε_(B)−ε_(A)). The shape changeavailable in the SMA, using UM, is thus self-actuated, rather thanthermally actuated and controlled, permitting greater control over adevice incorporating the SMA.

The key difference between the material properties of the SMAs shown inFIGS. 1 and 2 is the relationship between the SMA A_(f) temperature andthe normal body temperature of a patient. As the A_(f) temperature isadjusted downwardly, the hysteresis region bound by the path O, A, B, C,D, E, O is raised, thus increasing internal stress at a given straincondition.

UM can be produced in an SMA having an A_(f) temperature set below bodytemperature by freezing the alloy to a temperature well below its A_(f)temperature (so that it behaves like the material shown in FIG. 1);loading the alloy to point C (and possibly then unloading the alloy topoint D), as in FIG. 1; constraining the SMA in either the deformedshape while at point C or D, and then elevating the temperature of theSMA to human body temperature (which is above A_(f)), while constrainingthe alloy (e.g., in a catheter or a delivery device) while at points Cor D, as shown in FIG. 2. In this condition, the SMA comprises UM, whichwill impart force on the constraining catheter, thus generating aself-actuating driving force directed to achieving a lower strain statemore nearly at point E or eventually, at point O, in FIG. 2. In thiscase, the SMA is conditioned to a state of UM through athermal-mechanical process. The martensite is thermally induced bycooling the SMA and then imparting stress and warming, and the deformedalloy is thus constrained in a state of UM.

FIG. 3 illustrates a stress versus strain path performed by a mitralvalve reshaping device as it is loaded into a constraining catheterand/or delivery device, deployed, and then adjusted to enhance itsstiffness after being deployed within the coronary sinus. By applyingstress, strain, or a thermo-mechanical process as described above, theSMA can be conditioned to a state of UM at a point between point A andpoint C in FIG. 3. It is in this condition that the device would bepositioned in the coronary sinus for use in reshaping the mitral valveannulus. Upon deployment in the coronary sinus, the reshaping device isreleased from its constraining delivery device, reducing stress to apoint E (as shown in FIG. 3). Point E has been arbitrarily chosen as apoint of reduced strain at which the device has applied force to thecoronary sinus tissue and has come to a state of balanced forceequilibrium with that tissue. This example illustrates how a device madefrom SMA material and conditioned to a state of UM, can reliably performwork on tissue in the remote location of the human coronary sinus as aself-actuated single component.

Moreover, by applying an external force to assist the mitral valvereshaping device to even further displace the surrounding coronary sinustissue, the material stiffness of the SMA comprising the device can beadjusted and enhanced. For example, by assisting the SMA of the deviceto a lower strain state, such as a point F, the device can be stiffenedusing stored energy arising from the elasticity of the deformed tissue.As the assisting load is removed, the elastic recoil of the tissue willpush the reshaping device towards a higher strain state, i.e., towardsor beyond point G. The slope between F and G represents the new modulusof rigidity of this mitral valve annulus reshaping device. As the SMA inthe device is allowed to relax to a lower strain state, its strain levelwill move onto the lower plateau curve. As the SMA is forced to a higherstrain state, the strain level will move to the upper plateau curve.Therefore, by forcing the device to a higher or lower strain state, amitral valve annulus reshaping device can be advantageously adjusted toa required stiffness to reshape the mitral valve annulus as needed toreduce mitral valve regurgitation. The ability to reversibly changebetween the austenitic and martensite states after the device has beendeployed in the body of the patient provides greater flexibility andcontrol of a mitral valve annulus modification using the presentinvention.

It will be understood that each of the embodiments discussed below canbe implemented using SMA produced in accord with the precedingdiscussion. At least a portion of the SMA may be in an austenitic statewhen introduced into the body of a patient and then changed, at leastpartially, to a martensite state. Preferably, however, the SMAcomprising the device will be constrained and introduced into thepatient's body as UM. The UM state of the device can be achieved usingany of the approaches discussed above.

FIG. 4 illustrates a human heart 20 in which the atria has been removedto expose a mitral valve 22, an aortic valve 24, and a tricuspid valve26. Also partially shown are a circumflex artery 36 and a coronaryartery 38. Mitral valve 22, which is located between the aorta and leftventricle, includes an anterior cusp 28 and a posterior cusp 30.Surrounding the anterior cusp and posterior cusp is an annulus 32 thatmaintains the spacing of the cusp when a mitral valve closes during aleft ventricular contraction. Coronary sinus 34 extends adjacent toannulus 32, along the atrial ventricular groove between the left atriumand left ventricle of the heart. Since coronary sinus 34 is generallycoplanar with annulus 32, it is ideally disposed to facilitatemodification of the shape of the annulus to correct a leakage or bloodregurgitation problem with the mitral valve. The present invention takesadvantage of the disposition of the coronary sinus relative to theannulus of the mitral valve by enabling insertion of a device into thepatient's body, for modifying the shape of the annulus from within thecoronary sinus.

Various known techniques can be employed for inserting a catheter intothe coronary sinus through a venous incision to enable deployment of amitral valve annulus device in accord with the present invention. Forexample, it is contemplated that the mitral valve annulus reshapingdevice can be constrained within a catheter in preparation for insertionwithin the coronary sinus, and the catheter can then be guided into thecoronary ‘sinus, using a guide wire or other appropriate means. Oncethus in place, the reshaping device can either be pushed from thecatheter, or the catheter can be pulled back, leaving the device in adesired position within the coronary sinus.

FIG. 5 illustrates apparatus that facilitates a preferred approach forinserting a catheter 40 into coronary sinus 34. This apparatus includesa pre-curved inner dilator 54, which can be manually shaped into a curveto match the anatomical characteristics of the patient, and which has aproximal end 52 that extends proximally of catheter 40. The pre-shapedcurve in inner dilator 54 enables advancing the dilator around arelatively sharp bend, as is necessary to enter the coronary sinus. Theinner dilator is used to advance the catheter through the patient'svenous system and into the coronary sinus, pushing, rotating, andmanipulating the dilator as required. When positioned as required fordeployment of the reshaping device, the catheter will typically extendfrom an incision in the patient's jugular vein (not shown) and downthrough the vena cava. From the superior vena cava, the catheter willextend into the right atrium of the heart, and continue along the wallof the right atrium and into the coronary sinus. Once the inner dilatorand catheter 40 have been advanced so that the distal end of thecatheter is disposed where desired within the coronary sinus 34, thepre-curved inner dilator is withdrawn to enable insertion of the mitralvalve annulus reshaping device.

FIG. 6 illustrates an assembly that is preferably used for introducing amitral valve annulus reshaping device into the coronary sinus throughcatheter 40. The assembly includes a cartridge 42 within which themitral valve annulus reshaping device is constrained in a UM state. Asshown in FIG. 6, cartridge 42 is coupled to the proximal end of catheter40 to facilitate deployment of the mitral valve annulus reshaping deviceinto the coronary sinus through the catheter. A pusher cable 46 extendsfrom a handle 48. The distal end of handle 48 includes a snap lock 45that engages a control knob 44, locking handle 48 onto control knob 44,while still enabling the control knob to be rotated in engagement withthreads (not shown) that are formed on the exterior surface of cartridge42. As handle 48 is brought into engagement with the control knob,pusher cable 46 advances the mitral valve annulus reshaping device frominside cartridge 42 into catheter 40 and toward the distal end of thecatheter.

Once handle 48 has fully engaged and been locked onto control knob 44,the mitral valve annulus reshaping device should have been advanced to apoint just within the distal end of catheter 40. Control knob 44 is thenrotated in engagement with the threads on the outside of the cartridge,to advance the mitral valve annulus reshaping device from the constraintof catheter 40, into the coronary sinus of the patient. Thus, controlknob 44 controls the advancement and deployment of a mitral valveannulus reshaping device within the coronary sinus. A release knob 50 isemployed for uncoupling pusher cable 46 from the device after it hasbeen fully deployed within the coronary sinus and adjusted as desired bythe medical personnel using-the assembly. Once the mitral valve annulusreshaping device is fully disposed within the coronary sinus, catheter40 is withdrawn from the patient's body.

FIG. 7 illustrates the disposition of catheter 40 within the coronarysinus while a mitral valve annulus reshaping device 60 remains insidethe catheter 40, ready to be deployed within coronary sinus 34. As shownin this Figure, the mitral valve annulus reshaping device has a distalend 62 that is generally aligned with the distal end of catheter 40,while a proximal end 64 of the device is well inside catheter 40. FIG. 7thus shows the disposition of the mitral valve annulus reshaping deviceprior to rotating control knob 44 to force the device from insidecatheter 40 so that it is released and unconstrained within the coronarysinus.

While the mitral valve annulus reshaping device remains constrainedwithin catheter 40, the shape memory alloy comprising the reshapingdevice at least partially remains as UM. The shape memory alloycomprising the device has a characteristic temperature, A_(f), that isbelow or equal the normal body temperature of the patient. Accordingly,the SMA is in a super-elastic state, and the device can readily bedelivered into the coronary sinus through catheter 40 while constrainedin the UM state. Because the SMA of the device is super-elastic, thedevice is readily deformed to a size that fits within the catheter andcan be advanced into the coronary sinus. The interior surface of thedistal portion of catheter 40 or the exterior surface of the mitralvalve annulus reshaping device can be coated with a friction reducingmaterial, such as a lubricating material or the catheter provided with alow friction lining material to facilitate deployment of the device fromthe distal end of the catheter.

The SMA comprising the mitral valve annulus reshaping device 60 at leastpartially converts from UM to its austenitic state once released fromthe constraint of the catheter as is illustrated in FIG. 8. As shown inthis Figure, reshaping device 60 is fully outside of the catheter anddeployed within the coronary sinus. Once the constraint of the catheteris removed, the mitral valve annulus reshaping device is enabled tochange to a second, relatively lower strain state having a reducedradius of curvature, so that a distal end of the device exerts a forceagainst the annulus of the mitral valve. This release from theconstraint imposed by the catheter enables at least a partial recoveryto the programmed shape of the device. The mitral valve annulusreshaping device is constrained so that its programmed shape curves witha reduced radius substantially in the plane of the mitral valve annulus,bringing the distal end of the device into contact with and exertingforce upon the annulus as shown in FIG. 8. If desired, a removabletether (as shown in FIGS. 10 and 11) can, be employed to further reducethe radius of curvature of the reshaping device to reduce its internalstrain condition. Once the force applied by the tether is released, anelastic recoil of the tissue on the inner surface of the coronary sinusthat is in contact with the device will again load the SMA of thedevice, causing the strain to increase, as shown along line FG in FIG.3. Use of the tether in this manner thereby enables adjustment of themitral valve annulus reshaping device stiffness and the force atequilibrium with the tissue that the reshaping exerts against theinterior surface of the coronary sinus at distal end 62, to reshapeannulus 32.

Alternatively, the SMA of the device can be modified to have lessstiffness. The reduced radius of curvature of the annulus in FIG. 8 isin contrast to the increased radius of curvature of the annulus as shownin FIG. 9. In this case, the programmed shape of mitral valve annulusreshaping device 60 has been modified using a straightening rod (notshown) that is inserted through the catheter, before the catheter isremoved from the venous system of the patient. The straightening rod canbe temporarily advanced into the coronary sinus, to act upon the mitralvalve annulus reshaping device so as to increase the radius of curvatureof the reshaping device and thereby reduce internally stored strain. Inthis manner, the straining rod is used to adjust the mitral valveannulus reshaping device stiffness and reduce the normal force appliedby the reshaping device against the tissue of the coronary sinusadjacent to the mitral valve annulus. By monitoring physiologicalparameters such as blood pressure, fluoroscopic images, ultrasound flowpatterns through the heart, and an electrocardiogram of the patient,medical personnel can determine the effect of reshaping the annulus ofthe mitral valve and modify the extent of the reshaping as necessary toachieve a desired improvement in the functioning of the mitral valve.Clearly, a physician will desire to provide an optimal correction of adefect in the mitral valve, and the present invention provides the meansto vary the degree to which the annulus is reshaped and thereby controlthe changes to the mitral valve operation as desired.

FIGS. 10 and 11 illustrate a mitral valve annulus reshaping device 70that can readily be modified once it has been disposed within thecoronary sinus of a patient. In this embodiment, device 70 is pushedfrom catheter 40 (not shown in this Figure) using a pusher 72, which canremain in place after catheter 40 has been partially withdrawn. Coupledto device 70 is a tether 80, which extends through a lumen 82 in pusher72 and through a plurality of bores 78 formed within guides 74 that aredisposed at spaced apart locations along the longitudinal access ofdevice 70. An end terminal 76 is disposed at the distal end of mitralvalve annulus reshaping device 70, and tether 80 also extends throughbores 78 within end terminal 76, and loops back through bores 78 in eachof guides 74, extending out through lumen 82 in pusher 72 to theproximal end of the pusher, which is disposed outside the body of thepatient (not shown). As illustrated in FIG. 10, when unconstrained bycatheter 40, reshaping device 70 at least partially converts from UM toits austenitic state in which it attempts to assume its programmedcurved shape. Since the characteristic temperature A_(f), is below thenormal body temperature of the patient, the austenitic state can beachieved, at least partially, while mitral valve annulus reshapingdevice 70 is within the body of the patient. As is most clearlyillustrated in FIG. 11, tether 80 can be pulled while holding pushercatheter 82 against the proximal end of device 70, to assist the devicein applying force against the adjacent tissue of the coronary sinusafter the reshaping device has been deployed within the coronary sinus.Using the tether end pusher catheter 72 in this manner, it is possibleto reduce the reshaping device radius of curvature and thereby reduceits internally stored strain condition, until the tether is released,which then increases the loading and strain on the device. As discussedabove, the effect of this increase in the strain experienced by thereshaping device is to modify the stiffness of the device. Accordingly,it should be apparent that the tension applied by tether 80 is usable toadjust the stiffness of the mitral valve annulus reshaping device andthereby vary the force that it applies against tissue adjacent to themitral valve annulus within the coronary sinus. Once the desiredstiffness and force have been achieved by mitral valve annulus reshapingdevice 70, one end of tether 80 can be released, and the other endpulled to withdraw the tether through bores 78. The pusher catheter 72can then be withdrawn from the venous system of the patient, leavingdevice 70 in place.

As shown in FIG. 12, the second state and programmed shape of the SMAcomprising a mitral valve reshaping device 90 and its placement in thecoronary sinus can be chosen to cause an increase in the radius ofcurvature of the annulus when the constraint of the catheter is removed,in contrast to the decrease in radius of curvature of the annulus causedby the embodiment of FIGS. 8 and 9. For some patients, an increase inthe radius of curvature of the annulus may be preferred to a decrease inthe radius of curvature to correct problems with leakage through themitral valve.

FIGS. 13 and 14 illustrate a mitral valve annulus reshaping device 100that includes helical coil spring 102 disposed between straight wiresections 104 and 106. The helical coil spring is preferably formed ofSMA. A distal anchor 108 is also formed from SMA and is initiallydeployed and permitted to at least partially change from UM to itsaustenitic state as the device is initially pushed (and/or pulled) fromcatheter 40 (not shown in this view). For this embodiment, catheter 40is initially positioned within coronary sinus 34 at a location such thatas mitral valve annulus reshaping device 100 is forced from the distalend of the catheter and distal anchor 108 is allowed freedom from theconstraint of the catheter, the distal anchor 108 will change from itsUM state toward its austenitic state in which it has a loop shape with arelatively larger radial extent than when constrained inside thecatheter. The released loop expands radially outward and engages theinterior surface of the coronary sinus, over a distributed area.Thereafter, the catheter is withdrawn further, beyond helical coilspring 102, finally enabling a proximal anchor 110 to be freed from theconstraint of the catheter. The proximal anchor also at least partiallychanges from the UM state toward the austenitic state, enabling theexpanding loop shape of the proximal anchor 110 to anchor device 100 atits desired disposition within the coronary sinus.

Prior to deploying and releasing the constraint on proximal anchor 110,the user will apply tension to a tether line 112. The tether line formsa double loop around and through the distal and proximal ends of helicalcoil spring 102. The tensile load resulting from the application of atensile load on the tether line will cause straight wire sections 104and 106 and helical coil spring 102 to form UM. The proximally appliedtension in the tether line pulls the distal anchor, straight wiresection 104, and tissue distal to the helical coil spring in theproximal direction. The helical coil spring will thus be assisted torelax to its tightly wound programmed shape, which is therefore at alower strain state. Upon release of the tension produced by the tetherline, elastic tissue recoil and internal heart pressure will load thepreviously relaxed helical coil spring and transform the springstiffness to a higher level. Thus, by applying tensile load to thetether line, the reshaping device spring stiffness and length areadjusted to an appropriate level required to reshape adjacent tissue andthe mitral valve annulus, and thereby reduce mitral valve regurgitation.Also, the tension applied to tether line 112 determines the forceapplied against the adjacent tissue to modify the shape annulus 32,before the final disposition of proximal anchor 110 is determined.

In FIG. 14, spring stiffness has been increased in the helical coil 102causing the mitral valve annulus reshaping device to straighten theadjacent tissue and annulus 32. FIG. 14 also illustrates the reshapingdevice after tether line 112 has been removed, which is accomplished byreleasing one end of the tether line and pulling the tether line fromthe loops around the coils of the helical coil spring.

Yet another embodiment of the present invention is shown in FIG. 15wherein a mitral valve annulus reshaping device 120 is illustrated. Thisdevice also includes a helical coil 122, which is disposed betweenstraight sections 124 and 126 a tether 132 for adjusting the stiffnessof the spring and the relative force applied by the device against theadjacent tissue and mitral valve annulus. However, mitral valve annulusreshaping device 120 includes a distal stent 128 and a proximal stent130 that are also preferably formed of SMA. Distal stent 128 is allowedto expand as it converts from UM toward its austenitic state once theconstraint of the catheter is removed. Thus, once again it is importantthat the distal end of catheter 40 be disposed within coronary sinus atabout the location where distal stent 128 is to be disposed as it isallowed to expand to its programmed shape. By applying appropriatestress on tether line 132, the user can modify the tension distal ofhelical coil 122 and thereby achieve a desired modification of annulus32. In addition, the user can modify the strain and stress by varyingthe tension in tether line 132 to change the force applied to theadjacent tissue by device 120, using the tether line to change thestress applied to the helical coils of the SMA comprising the device.Accordingly, mitral valve annulus reshaping device 120 is very similarto the embodiment shown in FIGS. 13 and 14. As an alternative, it iscontemplated that one or both of the distal and proximal stents of thisembodiment might be made of a non-SMA metal, or of an SMA metal whoseA_(f) is above normal body temperature, and expanded radially intocontact with the interior surface of the coronary sinus using aconventional catheter inflatable balloon coupled to an external sourceof a pressurized fluid.

FIGS. 16-18 illustrate another embodiment of the mitral valve annulusreshaping device that includes an SMA metal wire or arched leaf spring140 with a programmed shape having a relatively small radius ofcurvature, R. At each end of arched leaf spring 140 are disposed loops142 and 144, also preferably formed of super-elastic SMA so that theyelastically expand radially outward when released from a catheter orother restraint that is used to insert the mitral valve annulusreshaping device intravenously into coronary sinus 34 of a patient. Whenthe device is released from the constraint of the catheter or otherdevice that is used to introduce the device into the coronary sinus, theSMA metal comprising the device it will change from its UM state towardits austenitic state. Thus, when loop 142 is released from the catheter,the expansion of loop 142, as the SMA material comprising it returns toits programmed shape, will bring the loop into contact with the innersurface of coronary sinus 34, so as to anchor the distal end of themitral valve annulus reshaping device at a desired location andorientation within the coronary sinus.

A tether 146 passes through loop 144, and both ends of the tether extendoutside the patient's body through the venous system within the catheter(not shown), enabling medical personnel to apply tension to the tetherafter the distal end of arched leaf spring 140 has been deployed withinthe coronary sinus and anchored by loop 142. Using tether 146, it ispossible to applying loading tension to arched leaf spring 140, therebyadjusting the stiffness of the arched leaf spring and the relative forceapplied by the device against the adjacent tissue and mitral valveannulus, prior to releasing loop 144 from the constraint of thecatheter. The applied tension tends to straighten arched leaf spring140, so that it has a greater radius of curvature, R′, as shown in FIG.17, when fully deployed within coronary sinus 34. The tension applied bytether 146 is then partially unloaded. Tether 146 can be employed tomake further adjustments to the device by loading and unloading thetension applied, reversibly tuning the device from UM to austenite andback. As shown in FIG. 18, the arched loop has been tuned in this mannerto have an even greater radius of curvature, R″, relative to its initialprogrammed curved radius of curvature, R, which is shown in FIG. 16.

Each of the embodiments disclosed above illustrates how SMA and itssuper-elasticity can be applied in modifying the shape of the annulusand thereby correcting defects in a mitral valve within the body of apatient. The characteristics of the SMA comprising each of theseembodiments, as illustrated in FIG. 3, is employed to good effect, sinceit permits the user to modify the stiffness of the SMA comprising thedevice and the force applied to the adjacent tissue by the SMA evenafter the mitral valve annulus reshaping device has been deployed in thecoronary sinus. The SMA can be reversibly changed between the martensiteand austenitic states while within the body of the patient, as necessaryto achieve a desired modification of the annulus and correspondingimprovement in the functioning of the mitral valve. By monitoring thephysiological condition of the patient, it is thus possible for medicalpersonnel to achieve a near optimum correction of a defect in a mitralvalve with the present invention, without the risks of open heartsurgery and with none of the problems associated with mitral valvereplacement.

Although the present invention has been described in connection with thepreferred form of practicing it, those of ordinary skill in the art willunderstand that many modifications can be made thereto within the scopeof the claims that follow. Accordingly, it is not intended that thescope of the invention in any way be limited by the above description,but instead be determined entirely by reference to the claims thatfollow.

1. A method of treating mitral valve regurgitation in a patient's heart,the method comprising: delivering a mitral valve device to a coronarysinus of the patient, the mitral valve device comprising a firstexpandable anchor, a second expandable anchor, and a connecting memberconnecting the first and second anchors; expanding the first anchor inthe coronary sinus from a delivery configuration and fixing the firstanchor to a portion of the coronary sinus; applying a proximallydirected force on the connecting member to pull the portion of thecoronary sinus to which the first anchor is fixed in the proximaldirection, wherein applying the proximally directed force causes theconnecting member to straighten and mitral valve regurgitation to bereduced; and expanding the second anchor within the coronary sinus froma delivery configuration and fixing the second anchor to a portion ofthe coronary sinus after mitral valve regurgitation has been reduced. 2.The method of claim 1 wherein expanding the first anchor in the coronarysinus comprises allowing the first anchor to self-expand.
 3. The methodof claim 1 wherein applying a proximally directed force on the connectorcomprises applying a proximally directed force on a central portion ofthe connector.
 4. The method of claim 1 wherein applying a proximallydirected force on the connector comprises applying a proximally directedforce on a spring portion of the connector.
 5. The method of claim 1wherein causes the connector to straighten causes a portion of themitral valve annulus to straighten.
 6. The method of claim 5 wherein aposterior portion of the annulus is straightened.
 7. The method of claim1 wherein expanding the second anchor comprises allowing the secondanchor to self-expand.